gms | German Medical Science

Comparative and functional genomics are powerful tools to advance the understanding of the molecular basis of cancer. Breast carcinoma is a complex disease characterized by accumulation of multiple genetic alterations, and the understanding of the molecular basis of mammary tumorigenesis is still incomplete. To identify molecular mechanisms involved in breast carcinogenesis, we analysed gene-expression profiles of normal breast tissue, ductal carcinoma in situ (DCIS), and invasive ductal carcinoma using six surgical specimens of two patients. As DCIS or ductal breast carcinomas usually contain a variable proportion of cancer cells in the tumor mass, we prepared at least 95% pure populations of tumor cells by means of laser microdissection (PALM Microlaser, Bernried), and compared their expression profiles to those of similarly purified, normal breast cells. To generate expression profiles we used U133A cDNA microarrays containing 22.283 probe sets (Affymetrix, Santa Clara, CA). Laser microdissection of 5.000 to 15.000 single cells and subsequent linear amplification is a time-consuming but reproducible approach to get high purified target cells in sufficent RNA quality. We identified various genes that were commonly up- or downregulated in breast tumor cells. Because of the high purity of the cell populations, a large proportion of genes were different from those reported in previous studies. These genome-wide expression profiles should provide useful information for finding candidates genes involved in breast tumorigenesis. The products of described genes might serve as specific tumor markers or as target for therapeutic strategies.